The fundamental goal of glaucoma management is to prevent patients from developing visual impairment that is sufficient to produce disability in their daily lives and impair their health-related quality of life (HRQOL). The overall goal of the Diagnostic Innovations in Glaucoma Study (DIGS): Functional Impairment is to improve understanding of functional disability in glaucoma and how it relates to commonly performed clinical tests. This proposal will obtain measures of functional impairment in a well-defined cohort of glaucoma patients that has been followed for over 15 years with a very large variety of clinical functional and structural tests. Cross-sectional and longitudinal investigations will address the following 3 specific aims: 1) to objectively evaluate functional impairment in glaucoma using performance-based tests: driving simulation and the Assessment of Disability Related to Vision (ADREV) scale, 2) to improve understanding of HRQOL deterioration in glaucoma using patient-reported outcomes and 3) to predict which patients are at risk for functional impairment and decrease in HRQOL from glaucoma. In Specific Aim 1, we will study the relationships between performance-based measures of functional impairment and standard clinical tests for assessment of glaucomatous optic disc and retinal nerve fiber layer damage. The investigation of these relationships will help link the results obtained by conventional testing to information related to disability from the disease and, therefore, may have significant impact on how results from different clinical tests are used for decision making and as surrogate endpoints in clinical trials of glaucoma. In Specific Aim 2, we will investigate factors that determine patients' perceptions of impairment from glaucoma by studying the longitudinal associations between subjective (HRQOL questionnaires) and objective (performance-based) measures of functional impairment and how they are related to results of clinical tests, demographic and socio-economic factors. This will identify the reasons why some aspects of impairment are more perceptible or bothersome to patients than others and may assist in the development of strategies to compensate or minimize the impact of disability in the daily lives of glaucoma patients. In Specific Aim 3, we will evaluate the ability of baseline and longitudinal structural and functional measures in predicting which patients are at highest risk for development of functional disability. The goal is to develop predictive models that can be used for identification of patients at higher risk for functional impairment, leading to a more efficient management of glaucoma and ultimately to a reduction of disability from the disease. By evaluating measures of functional impairment and developing predictive models to identify patients at risk for disability, this proposal directly addresses the current National Eye Institute National Plan for Eye and Vision Research goal of developing diagnostic methodologies to prevent vision loss from glaucoma.